The boss punished him ______ he should make the same mistake aga

The boss punished him ______ he should make the same mistake again.
A、incase of
B、unless
C、lest
D、so that
【正确答案】：C
【题目解析】：lest意为“以防万一”，引导从句用虚拟语气，形式为should+原形。